AB0050 EVALUATION OF THE ASSOCIATION BETWEEN CIRCULATING NON-CODING RNA CIRC_0005567 AND DISEASE ACTIVITY IN PATIENTS WITH RHEUMATOID ARTHRITIS AND ITS BIOLOGICAL FUNCTION IN THE CELL LINE MODEL
Authors: M. Ciesla, K. Kwasniak, B. Kolarz
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Rheumatoid arthritis (RA) is a chronic, autoimmune disease that leads to chronic inflammation of synovial tissue, ultimately causing joint damage, disability and premature mortality. Disease affects about 1% of the global population. Circular RNAs (circRNAs) are non-coding molecules and are generated through back splicing, during which the 5 ' and 3′ ends are covalently joined. Consequently, the lack of free ends makes them stable and resistant to exonucleases, and they become more suitable biomarkers compared with linear RNAs such as microRNAs (miRs) or long non-coding RNAs. CircRNAs are still poorly understood molecules in relation to RA pathogenesis. <h3>Objectives</h3> The aim of the study was to find an association between circ_0005567 plasma levels and disease activity in RA patients and to evaluate its molecular function. <h3>Methods</h3> A total of 66 individuals, 39 RA patients, and 27 healthy controls. RA patients were selected based on disease activity and RA patients with high disease activity (DAS28 &gt;5,1) and remission (≤2,6) were included. RNA was extracted from plasma and quantitative real-time PCR was used to analyze concentration of circ_0005567. The SW982 cell line was cultured in Dulbecco's Modified Eagle's Medium and supplemented with 10% fetal bovine serum. The cell line was grown at 37 °C, in a humidified atmosphere, with 5% CO2. The circ_0005567 silencing was performed by designed small interfered RNAs (siRNAs). Bioinformatic analysis was applied to select the miRs and mRNAs that may interact with circ_0005567. The expression levels of microRNAs were evaluated, subsequently the expression levels of selected mRNAs were performed. The expression levels of miRs and mRNA were evaluated at three time points: after 24h, 48h, and 72h. <h3>Results</h3> The expression level for circ_0005567 in RA patients was elevated compared to the control group (mean±SD; 173.6±123.8 vs 108.9±81.03, p=0.017). The molecule also showed significant differences in disease activity. Patients with high disease activity had about 70% higher concentration of circ_0005567 than the control group (186.99 vs 108.9, p=0.015). In the cell line model we found an association between silencing circ_0005567 and elevated miR-194 concentration and elevated concentration of three mRNAs: <i>KPNA1, HBEGF, TLN2.</i> <h3>Conclusion</h3> The expression of circ_0005567 was related to genes that are significant for the pathogenesis of RA. For example, <i>HBEGF</i> gene expression in fibroblasts plays a role in the remission of rheumatoid arthritis, and <i>KPNA1</i> was reported as seed gene related to RA. Due to the fact that circRNAs are stable and resistant to degradation, plasma concentration of circRNAs may be a new potential epigenetic markers of RA and disease activity. <h3>References</h3> [1]Panda AC, Dudekula DB, Abdelmohsen K, Gorospe M. Analysis of Circular RNAs Using the Web Tool CircInteractome. Methods Mol Biol. 2018;1724:43-56. [2]Sabir JSM, El Omri A, Banaganapalli B, et al. Dissecting the Role of NF-κb Protein Family and Its Regulators in Rheumatoid Arthritis Using Weighted Gene Co-Expression Network. Front Genet. 2019;10:1163. [3]Chen N, Fan B, He Z, Yu X, Wang J. Identification of HBEGF+ fibroblasts in the remission of rheumatoid arthritis by integrating single-cell RNA sequencing datasets and bulk RNA sequencing datasets. Arthritis Res Ther. 2022;24(1):215. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.